#!/usr/bin/env zsh
# -------------------------------------------------------------------------------------------------
# Copyright (c) 2010-2011 zsh-syntax-highlighting contributors
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification, are permitted
# provided that the following conditions are met:
#
#  * Redistributions of source code must retain the above copyright notice, this list of conditions
#    and the following disclaimer.
#  * Redistributions in binary form must reproduce the above copyright notice, this list of
#    conditions and the following disclaimer in the documentation and/or other materials provided
#    with the distribution.
#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
#    may be used to endorse or promote products derived from this software without specific prior
#    written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# -------------------------------------------------------------------------------------------------
# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
# vim: ft=zsh sw=2 ts=2 et
# -------------------------------------------------------------------------------------------------


# -------------------------------------------------------------------------------------------------
# Core highlighting update system
# -------------------------------------------------------------------------------------------------

# Array declaring active highlighters names.
typeset -ga ZSH_HIGHLIGHT_HIGHLIGHTERS

# Update ZLE buffer syntax highlighting.
#
# Invokes each highlighter that needs updating.
# This function is supposed to be called whenever the ZLE state changes.
_zsh_highlight()
{
    setopt localoptions nowarncreateglobal

    # Store the previous command return code to restore it whatever happens.
    local ret=$?

    # Do not highlight if there are more than 300 chars in the buffer. It's most
    # likely a pasted command or a huge list of files in that case..
    [[ -n ${ZSH_HIGHLIGHT_MAXLENGTH:-} ]] && [[ $#BUFFER -gt $ZSH_HIGHLIGHT_MAXLENGTH ]] && return $ret

    # Do not highlight if there are pending inputs (copy/paste).
    [[ $PENDING -gt 0 ]] && return $ret

    # Reset region highlight to build it from scratch
    region_highlight=();

    {
	local cache_place
	local -a region_highlight_copy
	
	# Select which highlighters in ZSH_HIGHLIGHT_HIGHLIGHTERS need to be invoked.
	local highlighter
	for highlighter in $ZSH_HIGHLIGHT_HIGHLIGHTERS; do
	    
	    # eval cache place for current highlighter and prepare it
	    cache_place="_zsh_highlight_${highlighter}_highlighter_cache"
	    typeset -ga ${cache_place}
	    
	    # If highlighter needs to be invoked
	    if "_zsh_highlight_${highlighter}_highlighter_predicate"; then
		
		# save a copy, and cleanup region_highlight
		region_highlight_copy=("${region_highlight[@]}")
		region_highlight=()
		
		# Execute highlighter and save result
		{
		    "_zsh_highlight_${highlighter}_highlighter"
		} always {
		    eval "${cache_place}=(\"\${region_highlight[@]}\")"
		}
		
		# Restore saved region_highlight
		region_highlight=("${region_highlight_copy[@]}")
		
	    fi

	    # Use value form cache if any cached
	    eval "region_highlight+=(\"\${${cache_place}[@]}\")"
	    
	done
	
	# Set zle_highlight according to user definition on this package level
	zle_highlight=(default:$ZSH_HIGHLIGHT_STYLES[default] isearch:$ZSH_HIGHLIGHT_STYLES[isearch] region:$ZSH_HIGHLIGHT_STYLES[region] special:$ZSH_HIGHLIGHT_STYLES[special] suffix:$ZSH_HIGHLIGHT_STYLES[suffix])

	# Bring back region higlighting from zle_highlight array (was overwriten by region_highlight)
	((REGION_ACTIVE)) && region_highlight+=("$((CURSOR < MARK ? CURSOR : MARK)) $((CURSOR > MARK ? CURSOR : MARK)) ${${(M)zle_highlight[@]:#region*}#region:}")
	
    } always {
	_ZSH_HIGHLIGHT_PRIOR_BUFFER=$BUFFER
	_ZSH_HIGHLIGHT_PRIOR_CURSOR=$CURSOR
	return $ret
    }
}


# -------------------------------------------------------------------------------------------------
# API/utility functions for highlighters
# -------------------------------------------------------------------------------------------------

# Arrays used by highlighters to declare user overridable styles.
typeset -gA ZSH_HIGHLIGHT_STYLES
typeset -gA ZSH_HIGHLIGHT_FILES

# Whether the command line buffer has been modified or not.
#
# Returns 0 if the buffer has changed since _zsh_highlight was last called.
_zsh_highlight_buffer_modified()
{
    [[ "${_ZSH_HIGHLIGHT_PRIOR_BUFFER:-}" != "$BUFFER" ]]
}

# Whether the cursor has moved or not.
#
# Returns 0 if the cursor has moved since _zsh_highlight was last called.
_zsh_highlight_cursor_moved()
{
    [[ -n $CURSOR ]] && [[ -n ${_ZSH_HIGHLIGHT_PRIOR_CURSOR-} ]] && (($_ZSH_HIGHLIGHT_PRIOR_CURSOR != $CURSOR))
}


# -------------------------------------------------------------------------------------------------
# Setup functions
# -------------------------------------------------------------------------------------------------

# Rebind all ZLE widgets to make them invoke _zsh_highlights.
_zsh_highlight_bind_widgets()
{
    # Load ZSH module zsh/zleparameter, needed to override user defined widgets.
    zmodload zsh/zleparameter 2>/dev/null || {
	echo 'zsh-syntax-highlighting: failed loading zsh/zleparameter.' >&2
	return 1
    }

    # Override ZLE widgets to make them invoke _zsh_highlight.
    local cur_widget
    for cur_widget in ${${(f)"$(builtin zle -la)"}:#(.*|_*|orig-*|run-help|beep|auto-*|*-argument|argument-base|clear-screen|describe-key-briefly|kill-buffer|overwrite-mode|push-input|push-line-or-edit|reset-prompt|set-local-history|split-undo|undefined-key|what-cursor-position|where-is)}; do
	case $widgets[$cur_widget] in

	    # Already rebound event: do nothing.
	    user:$cur_widget|user:_zsh_highlight_widget_*);;

	    # User defined widget: override and rebind old one with prefix "orig-".
	    user:*) eval "zle -N orig-$cur_widget ${widgets[$cur_widget]#*:}; \
                    _zsh_highlight_widget_$cur_widget() { builtin zle orig-$cur_widget -- \"\$@\" && _zsh_highlight }; \
                    zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;

	    # Completion widget: override and rebind old one with prefix "orig-".
	    completion:*) eval "zle -C orig-$cur_widget ${${widgets[$cur_widget]#*:}/:/ }; \
                          _zsh_highlight_widget_$cur_widget() { builtin zle orig-$cur_widget -- \"\$@\" && _zsh_highlight }; \
                          zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;

	    # Builtin widget: override and make it call the builtin ".widget".
	    builtin) eval "_zsh_highlight_widget_$cur_widget() { builtin zle .$cur_widget -- \"\$@\" && _zsh_highlight }; \
                     zle -N $cur_widget _zsh_highlight_widget_$cur_widget";;

	    # Default: unhandled case.
	    *) echo "zsh-syntax-highlighting: unhandled ZLE widget '$cur_widget'" >&2 ;;
	esac
    done
}

# Load highlighters from directory.
#
# Arguments:
#   1) Path to the highlighters directory.
_zsh_highlight_load_highlighters()
{
    # Check the directory exists.
    [[ -d "$1" ]] || {
	echo "zsh-syntax-highlighting: highlighters directory '$1' not found." >&2
	return 1
    }

    # Load highlighters from highlighters directory and check they define required functions.
    local highlighter highlighter_dir
    for highlighter_dir ($1/*/); do
	highlighter="${highlighter_dir:t}"
	[[ -f "$highlighter_dir/${highlighter}-highlighter.zsh" ]] && {
	    . "$highlighter_dir/${highlighter}-highlighter.zsh"
	    type "_zsh_highlight_${highlighter}_highlighter" &> /dev/null &&
		type "_zsh_highlight_${highlighter}_highlighter_predicate" &> /dev/null || {
		    echo "zsh-syntax-highlighting: '${highlighter}' highlighter should define both required functions '_zsh_highlight_${highlighter}_highlighter' and '_zsh_highlight_${highlighter}_highlighter_predicate' in '${highlighter_dir}/${highlighter}-highlighter.zsh'." >&2
		}
	}
    done
}


# -------------------------------------------------------------------------------------------------
# Setup
# -------------------------------------------------------------------------------------------------

# Try binding widgets.
_zsh_highlight_bind_widgets || {
    echo 'zsh-syntax-highlighting: failed binding ZLE widgets, exiting.' >&2
    return 1
}

# Resolve highlighters directory location.
_zsh_highlight_load_highlighters "${ZSH_HIGHLIGHT_HIGHLIGHTERS_DIR:-${${0:A}:h}/highlighters}" || {
    echo 'zsh-syntax-highlighting: failed loading highlighters, exiting.' >&2
    return 1
}

# Reset scratch variables when commandline is done.
_zsh_highlight_preexec_hook()
{
    _ZSH_HIGHLIGHT_PRIOR_BUFFER=
    _ZSH_HIGHLIGHT_PRIOR_CURSOR=
}
autoload -U add-zsh-hook
add-zsh-hook preexec _zsh_highlight_preexec_hook 2>/dev/null || {
    echo 'zsh-syntax-highlighting: failed loading add-zsh-hook.' >&2
}

# Initialize the array of active highlighters if needed.
[[ $#ZSH_HIGHLIGHT_HIGHLIGHTERS -eq 0 ]] && ZSH_HIGHLIGHT_HIGHLIGHTERS=(main) || true
